You are treating a patient who is complaining of chest pain. Upon your assessment, you note a 72 year old female who is stating that it feels like her heart is racing, which is causing her to have chest pain. Patient is breathing at 22 times per minute. Blood pressure is stable. You note that the patient has a heart rate of 184.
You perform a 12-lead ECG and note SVT. But, as you look more into the 12-lead, you notice that the rhythm is irregular irregular. Still, the heart rate is above 150, and is varying from 157-190, and everything in between.
You realize that your patient is stable, despite the chest pain, but everything else is normal. You decide to follow ACLS, and want to administer Adenosine. 6mg, then 12mg.
Now, let's think about this, before administering Adenosine. If your patient is in SVT, but you notice that the rhythm is irregular irregular, than it must be A-fib with RVR. We know that Adenosine works by effecting the re-entry pathways in the AV node, but, that's only with SVT. In A-fib, the atria and ventricles are not in key, so now matter how much you work on the AV node, the ventricles will still fire at will.
This patient needs a different type of antidysrhythmic, which we do not carry in the pre-hospital setting. The drug that is given, can vary.
Yet, if you do give Adenosine, it may work for a brief second, but your patient will almost always go right back into A-fib with RVR, and in some cases, may even worsen the A-fib with RVR.
Overall, you must always follow your protocol on treating SVT, and if A-fib with RVR is considered in the tachycardia protocol. My recommendation, and soly mine (ALWAYS FOLLOW PROTOCOL), is to call medical control, first, and confirm with them whether to or not to administer Adenosine.